This project seeks to develop new statistical techniques for problems in human development and to apply existing techniques to those problems in novel ways. In the past year, work focused on applications of statistical techniques to study a disease of childhood, attention-deficit/hyperactivity disorder (ADHD), and two neurological diseases of aging, amyotrophic lateral sclerosis (ALS) and Parkinson's disease. I have also assisted in the design and analysis of a clinical study to assess the hormonal effects of soy estrogen in the diets of neonates on their development. For ADHD, we have carried out a case-control study in a local school district and are currently working on describing the psychometric properties of the screening instruments used to assess disease status. We are also estimating ADHD prevalence among elementary school children in this county. For ALS, based on a case-control study that we conducted, we examined possible genetic modifiers of risk, finding some evidence that certain haplotypes of the vascular epithelium growth factor (VEGF)gene were associated with increased risk of ALS. The planning and preliminary work of the Parkinson's disease study is complete and field data collection is now underway. The pilot study of the effects of soy estrogen on neonatal development is now out of the field and analysis is beginning. We are examing physical markers of development using a modified Ballard scale, ultrasound images of putatively estrogen-sensitive organs, and hormone levels.